The present invention generally relates to probing tips for measurement probes and more particularly to an attachable/detachable probing tip system for a measurement probing system where the probing tips of the probing tip system are mountable on a device under test separate from other components of the measurement probing system.
Voltage measurement probes acquire electrical signals from a device under test and couple the acquired signal to a measurement instrument, such as an oscilloscope or the like, via an electrical cable. A typical voltage probe has a probe head with an electrically conductive hollow tube having a substrate disposed therein. The substrate has passive or active circuitry for conditioning the acquired signal prior to being coupled to the measurement instrument. The end of the hollow tube has an insulating plug disposed therein with a coaxially disposed probing tip extending out of the plug in both directions. The portion of the probing tip extending into the hollow tube is electrically connected to the substrate. Generally, voltage measurement probes are used in hand-held probing of a device under test or mounted to a probing arm that is positioned on the device under test. Excessive force applied to the measurement probe can break the probing tip requiring replacement. Generally, this requires the measurement probe to be sent to a service center where experienced technicians take the probe apart and replace the broken tip. This results in the loss of use of the probe during the repair period and the expense of the repair.
U.S. Pat. No. 6,466,000 describes a replaceable probe tip holder and measurement probe head that allows a user to replace a broken probe tip without sending it to a service center. The replaceable probe tip holder has a cap and attachment arms extending away from the back end of the cap that are positionable on the outside of a probe head housing. The cap has a series of cavities from therein and a bore extending from the innermost cavity to the front end of the cap. A resilient compression member is positioned in the innermost cavity and a probing tip is passed through the resilient compression member and disposed in the bore with the probing point extending outward from the cap. The other end of the probing tip is flared out to form a head that sandwiches the resilient compression member between cap and the probing tip head. Adjacent to the innermost cavity is a second cavity that receives a portion of a substrate that is disposed in a probe head housing. The end face of the substrate has at least a first electrical contact that mates with the head of the probing tip. A third cavity receives a portion of the probe head housing. It should be noted that the probing tip is not securely mounted in the cap of the replaceable probing tip holder and that the probing tip is only securely mounted in the replaceable probe tip holder when the holder is positioned on the probe head.
As the bandwidth of measurement increases, there is a corresponding need for measurement probes having equal or greater bandwidths. A major difficulty in designing very wide bandwidth measurement probes having bandwidths of 5 GHz and greater is the effects of capacitance and inductance of the probing tip or tips. One solution to this problem is to separate the probing tips from the active circuitry in the probing head of the measurement probe. U.S. Pat. No. 6,704,670 describes a wideband active probing system where the probing tip or tips of the probe are separable from a probe amplifier unit. One or more probe cables are connected to a probe tip unit which are connected to the probe amplifier unit for conveying signals received by a probe unit. Various types of probe tip units may be connected to the probe amplifier unit. The probe tip unit may contain circuitry ranging from conductor traces to various resistive, capacitive, and/or other electronic elements. An advantage of such a probe design is that it allows the placement of the substantially smaller probe tip unit onto difficult to reach contacts on a device under test instead of a larger measurement probe containing probe amplifier circuitry.
The probe tip unit may be single ended or differential and includes probe connection points for electrically connecting probing tip units to the probe tip unit. The probing tip units include a probing tip and may include impedance elements, such as resistors. The probing tip units are secured to the probe connection points of the probe tip unit by soldering or compression terminal connections. Various types of probing tip units may be soldered to the probe connection points, such as solder-on, plug-on, SMT grabber, and wedge probe tip units. The various probing tip units allow for changing the electrical characteristics of the probing system or replacing a damaged probing tip unit by de-soldering the existing probing tip unit and soldering replacement probing tip units to the probe connection points. A drawback to this design is that each probing tip unit needs to be soldered to one of the probe connection points. In addition, continued soldering and de-soldering of the probing tip units to the probe connection points run the risk of damaging the probing contact point resulting in the loss of the probe tip unit. Further, in certain differential and single ended probing applications, the probe tip unit needs to be soldered to the probing points of the device under test. This may require a user to populate the device under test with multiple probe tip units which drives up the probing solution cost.
What is needed is an attachable/detachable probing tip system for a measurement probe system where the probing tips are easily mounted on a device under test without being connected to other components of the measurement probing system. The probing tip system needs to be inexpensive and easily attachable to the rest of the measurement probing system without the use of soldering.